Standing wave ratio indicator



P 1952 A. v. HOLLENBERG 2,611,103

STANDING WAVE RATIO INDICATOR Filed Jan. 17, 1946 FIG. I

JA W 700 77/ GE/VB 70,2

INVENTOR. ARTHUR V. HOLLENBERG arroov' Patented Sept. 16, 1952 UN I T'ED STATES PATENT OFFICE j v 2,611,103 I WAVE BATH} INDIGATOR I Arthur v. Hollenberg, 1st. Alban assignor to, the. United. Stat-.esfof. America.- as; represented bythe Secretary'otfEW'ar f Application. January 17, 1946, S-erial'No. 641335 2; clai s... (0!..315-3).

'Ihisinventionrelates to measuring devicesand.

more. particularly to, electrical. apparatus: for measuring. the, standing; wave} ratio: in radio. frequency transmission. lines.

Aconventionalmeans for measuring the. stand-- ing; wave ratio in radio frequency transmission lines. employs a. Probe placed. in Bit-81013111 a length of wave guide, which. is adapted. to; be inserted in series with the... transmission. line. The probe is. moved alongv theslotin the, wave, guide: thereby enabling the potential at, various. points. to be measured and recorded... A graph may then. be

plottedof the potentials existing at points alongthe. wave guide against their displacementfrom a. fixed reference point. This method is laborious I and time consuming. In addition, the equipment employed, must. be carefully machined and adjusted. if satisfactory results are. to. be obtained,- It. is; an. object or this. invention, therefore. is

provide. a novel means. for measuring the. stand:- f

ing. wave. ratio. in a. transmission-1 line, that elim-.

mates. many oi the. difficulties encountered in.

previousmeasuring. methods. 1 It is a further objectof this. invention, to provid'emeans for producing a continuous. repre.-' sentation of the. standing waves present in a transmission line.

For a better understa-nding .ofthe invention,

together with other and further objects. thereof,

reference is had to the following description taken in connection with the accompanying drawing in which: Fig. l is a diagrammatic plan ent invention;

view of themesv Fig. 2, is a diagrammatic side view of thepresent. invention;

Fig. 3 is. a cross-sectional viewof the presentj.

invention taken along the line- 3:-3 of Fig. 1-; and.

Fig. 4 is a front View illustrating a typical pat tern upon the viewing screen of this invention. In Fig. 1 there is shown a cathode ray tube ID with a conventional electron gun l2, tube base l4 and a fluorescent screen [6. In the embodiment here illustrated, a pair of deflecting plates l8 are r provided so that suitable potentials applied there- 'to may deflect the electron beam in a predertermined manner. 7 action of thebeam is preferably produced by ap ri ht. angles; to; the: planeofi deflections. produced by potentials applied to, plates; [8. A metallic hollow-pipe wave guide 26 positioned. betweenda fleeting; platesjta and 24: is provided with. aligned slots located; in' the: planet of deflection; of platesl8. Wave guide 26 passes through the glass envelope of cathode ray tube; Ill and is; provided at. each: end. with. a. matched window sealed. to thewave guide. A glass to. metal seal is, made; at: the. points: that wave guide 26; passes; through thergl'ass: envelope of tube H). p

A diagrammatic side viewof the embodiment shcwnin. Fig. 1- isgiven. in Fig. 2, in whichlike parts have been. given like. reference numerals. Dotted. lines- 30 and. 32: represent, twoof, the many paths. that. the electron beam may follow after; deflection by plates; 24. In the; cross-sectionalview of theinvention, as. shown inrEig 3,. are best seenv the. previously mentioned;v aligned slots,

. designated: by the reference. numeral 34, and-the.

matching. windows 36 and 38 waveguide26. V Referring, now more particularly to theoperar. tion. of the presentinvention, cat hodie;rayptube.v 1.0. may be connected ina circuit,. that is similar to: a cathode ray oscilloscope circuit except as-to wave guide 26- anddeflecting. plates-2.4. as. will. appear. The. electron beam, is; focused. and ac celeratedby electron gunr 'I--2, and thh'eam; is. made tosweep back and. tenth; t aligned; slots. 34.; by means of arela-tivelyy low frequency; potential applied. to" plates 8- guidezt. is, v bwmeans; or windows; p matched into a transmissionline whose standing; wave characteristics: are; table -determined. necessary, additional matching, sections; may; be inserted between the endsof wave guide; and:-

at the two ends. ot

the. transmission. line. under testso; thatrtheqelecje itrical characteristicsofi thelineunder testareenot changed. The standing Wave conditions of the line are thus duplicated within wave guide 26. The electron beam in tube Ill passes through the two slots in wave guide 26 in directions substantially parallel to the directions of the electric field within this wave guide. As the electron beam is swept back and forth through the slots in wave guide 26, the velocity of the beam is continually changed by amounts proportional to the intensities and directions of-the rapidly varying electric field in wave guide 26 at the points of passage of the electron beam. The instantaneous magnitude of the change in velocity along a beam path varies sinusoidally with time in accordance with the variation of the electric field in wave guide 26, but

the limits of change in the beam velocity along in wave guide 26 are rapid relative to the sweeping action of the beam.

The electron beam leaving wave guide 26 passes.

between deflecting plates 24. In the cathode ray tube here described, a constant potential (lif ference is maintained between plates 24,'and the electron beam passing between the plates is thus deflected by amounts inversely proportional ,;to- This latter the square of the beam velocities. deflection is at right angles to the deflection of the electron beam caused by plates I8. Two such deflection'path's "caused" by plates 24' are illustrated-in Fig. '2 at 3B and. The electron beam uponstrilring screen [6 traces a pattern thatis indicative of the'standingwave conditions within wave gili de 26 and the transmission line to which itijs connected'.-" 3 a 1 Fig.4'=illustr'ates the; appearance of such a patterrihpon-scraen [-6 delineating standing wave conditions in a transmission line. -The envelope oithe pattern may actually contain many more cycles of oscillation traces than appear-inFig. 4, for v the frequency of "the wave energywithin the wave guide maybe-"extremely high compared to th' lateral sweep rate of theelectron beam. The pattern within the'envelope may further not bestationary; for such a condition obtains only at certain ra'tios of sweep-frequency to Wave guide energy frequency; The-"determination of the standing ave ratio is determined by measuremehts made upon the envelope itself; for-this en-' velope corresponds to the standingwa'vei ---"The standing wave ratio is thus given by 'the ratio of distance D; to'distance D'z' as designated "in'Fig." 4, anid the 'cathtidraY'tubeJ 0' maybe provided with meazis ror measuring these dis'ta'ncesr The apparat'us m y; furtherbe calibrated to indicate the grads-wavelengt ofth'e guideenergy, for it is proportional to v the distance between corresponding 'positioiis along the -"paittern*envelope, for ex;

ammathepositions Prand 'P'z shown in Fig. 4. "It is apparent-that further advantages of the invention here described" are i that Z the standing viaveratio n a" transmission line may bedet'er trneasurements upon arepre'senta a 'riicture of the'standing wave a transmission line appears "011' the screed-of entionthus providing instantaneous data nmwnmmg adjustment or; associatd *app'ara-tus; and there" are no moving parts in this in-' vention, so that careful adjustment and special techniques necessary with prior art devices for measuring standing wave ratios are eliminated.

While there has been described what is at present considered the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications maybe inade therein without departing from the spirit of the'invention.

,, What is claimed is:

l. A standing wave ratio indicator, comprising :an electron discharge device including an electron gun generating a beam of electrons along a first coordinate, firstdefiection means for periodically deflecting said beam along a second coordinate perpendicular to said first coordinate, an eleca tromagnetic wave transmission means providing astanding wave pattern in the path of said periodically deflected beam and having an elongated aperture, the long dimension of said aperture being-parallel tosaid second-coordinate, and said aperture being positioned to permit passage of said periodically deflected electron 'beam' through said means, wherebyfthe'elctroris said periodically deflected beamf maybe j'velocity modulated in accordance with said "standing wave pattern, second deflection means providing a 2'. The indicatoras'set forth in claim" 1, wh'ereir' i 7 said transmission means comprisesla length of rectangular waveguide having broad and narrow all it a e edi e e ed ots in the br ad walls thereof, the longg axes' of said slotsbeing parallel to said second coordinate, 'said"slots being positioned so a'sitopjermit as a e of said periodicallyfldeflected' beam of" electrons theree 1 "ARTHUR" vI O L m BBFE FNQE 'JQ TE ,Tlie, auewmg refer enees a r eco'rafm. the fil i it'i e lh- 1 2.4 8 Smullin et al. oct. 5, 4s 

